aussies fur

Question
first i do apologize for my rude behavior in my earlier question
i would done this sooner but i haven't gotten the chance.
anyways my Aussies fur is fine for the most part but on his back or spine? area he seems to have fur that's just somewhat loose or not filled in if u get what i am saying

we have never given him a haircut nor neglected his coat in anyway but it just seems to grow in a awkward fashion,he is an outside dog and doesn't get brushed to often at least once a week as of now. please help and thnaks

Answer
I appreciate your apology.  At this point, I really think you should take your dog to a vet.  Hair loss can be from a variety of things: fungal infections, demodex mites, Cushing's disease, etc.  Skin'haircoat issues can be a sign of hypothyroidism in dogs, especially if there is no itching.  That disorder is more prevalent in Aussies than some other breeds.
Dogs are sometimes allergic to certain shampoos, or may have contact allergies (dermatitis).  Some dogs are more sparsely coated than others.  Obviously, this is a concern to you, so my advice is not to assume that it's nothing, and spend the few dollars for an office visit so your vet can do a clinical exam on the dog.  Better safe than sorry.